Green Synthesis of Silver Nanoparticles Using Cynoglossum creticum Leaf Extract: Eco-Friendly Approach for Antibacterial, Antioxidant, and Sensing Applications

Nanotechnology leveraging renewable plant biomass to develop silver nanoparticles offers eco-friendly solutions with more sustainable applications. The present research explores the employment of an aqueous extract of Cynoglossum creticum leaves in the green synthesis of silver nanoparticles (Ccl-AgNPs) for potential biological and sensing purposes. The synthesis parameters were controlled spectrophotometrically, and the physicochemical characterizations of Ccl-AgNPs were evaluated. Phytochemicals in the extract served dual roles, as confirmed by infrared spectroscopy analysis. Thermogravimetric analysis (TGA) and energy-dispersive X-ray spectroscopy (EDS) further revealed the presence of a plant-derived organic matter on AgNPs. Morphological descriptions indicated the spherical form of Ccl-AgNPs, comprising a median size of 32 nm. Furthermore, the biological characteristics of green Ccl-AgNPs were investigated, as they showed promising antioxidant activities in DPPH, ABTS, reducing power, and phenanthroline assays. Ccl-AgNPs also exhibited a good inhibitory impact on the growth of four tested Gram-positive and Gram-negative bacteria. Pseudomonas aeruginosa was most susceptible to the inhibitory activity of Ccl-AgNPs, with a minimum inhibitory dose of 31.25 µg/mL. Colloidal AgNPs capped by Ccl-extract have established the potential for use as an SPR-based colorimetric sensing system for the selective detection of neomycin sulfate, with a limit of detection (LOD) of 2.88 µM. The colorimetric probe was successfully tested for neomycin sulfate detection in environmental and biological fluids and veterinary pharmaceutical preparations, with recovery rates ranging between 92.62 and 105.76%. This study underscores the potential of Cynoglossum creticum, a livestock-hazardous weed, as a sustainable resource for synthesizing silver nanoparticles for potential ecological and biomedical uses.